The present invention is directed to a method for providing error compensation for rolling master gears, master gear spindles, work spindles, work gear holding devices, and the like in a functional double flank gear checking apparatus.
Functional gear testing measures the total effect of gear errors. Also known as total radial composite deviation, testing of the gears involves determining how the gears operate when in contact with one another.
A method normally used to evaluate gear operational efficiency is double flank gear testing. In double flank gear testing, the gears are placed in a tight mesh, producing contact on both flanks of the gear teeth. Generally, the gear being inspected, the work gear, is mounted to a fixed arbor. A master gear is mounted to a fixed or adjustable slide and put in contact with the work gear.
When work gears and master gears are rolled together on rolling fixtures with either fixed or adjustable centers, dimensional variations during one revolution of the work gear may be determined. Variations caused by differing tooth thickness, nicks, cuts, and other imperfections cause a change in the center distance between a work gear and a master gear when rolled together in a tight mesh. In addition, variations in the incline or shape of the teeth are also measured, known as gear lead and gear taper.
Determining the accuracy of the work gear and error due to the work gear relies on the accuracy of the master gear and master gear spindle, as well as other components of the testing system. Gear testing devices currently available assume that the variations or discrepancies in gear rotation are due to imperfections in the work gear being tested. Precision master gears are used for intermeshing with the test or work gear during testing, such that it can be assumed that imperfections observed are due to defects in the test gear. Precision master gears are relatively difficult and expensive to produce. Even with such accurate gears, however, wear and/or damage may create irregularities in the precision master gear, giving imprecise readings.
Also present are errors from the master gear, the master gear spindle and the work gear arbor and spindle. The master gear and master gear spindle are used as references to collect test data and thus, must also be extremely accurate and frequently calibrated. However, unless the master gear and spindle are frequently calibrated and have a known error, the amount of error attributable to the work gear alone cannot be measured accurately because the error attributable to the work gear is only a portion of the total error present in the apparatus. The error found in known double flank gear testing methods is the total error of the system and does not isolate the error caused by the work gear. However, there is no simple way of determining solely the work gear error; in other words, there is no clear, easy way to isolate the error attributable to the work gear from the total error present in the system.
Accordingly, there is a need for a method to easily determine the error attributable to a work gear alone. Desirably, such a method uses the same displacement measurement device as is used for the actual double flank functional gear inspection. Also desirable would be a method that introduces no errors due to structural flexing into the error compensations. In addition, the complete compensation would be done automatically without variables induced by human intervention or inconsistencies, and leaving the operator free to attend to other requirements, thus significantly reducing the set-up change over time.